System outages can generally be categorized as being either planned or unplanned. Whether an outage is of one kind or another may not be apparent to an outer system or a user. A planned system outage can be the result of a planned activity by a system owner and/or by a service provider. Planned outages may be scheduled to perform maintenance, detect faults, provide software patches, and/or to otherwise modify system parameters. Planned outages can be carefully scheduled to minimize computer system downtime. For example, outages can be planned using a “rolling upgrade” process whereby portions of a system are incrementally taken down for upgrade, without affecting the overall functionality of the entire system.